(1) Field of the Invention
The present invention relates to the production of books and particularly to the automatic application of protective jackets to hard cover books. More specifically, this invention is directed to apparatus for wrapping paper-type jackets around books. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
(2) Description of the Prior Art
It is common practice to apply paper jackets to books prior to the shipment thereof from the printer to the retailer. Such jackets are printed in flat form, are subsequently wrapped around the book and are folded into the book cover. The application of jackets to printed books by hand is obviously not an economically feasible approach.
Prior art techniques for automatically applying jackets to books are exemplified by the disclosure of German Pat. No. 1,103,294. The referenced German specification describes a method in which books, with their spines facing downwardly, are placed upon unfolded jackets. The covers of the books are then opened outwardly, the "turn-ins" or flaps, comprising oppositely disposed edge portions of the jackets, are folded around the covers and the books are then reclosed. Jacketing machines which are designed to operate in accordance with this prior art method have provided less than satisfactory results. The unsatisfactory results are, at least in part, due to the stiffness and resiliency of the jacket materials which often cause reopening of the book covers which allows the jacket flaps to slip out. Should this happen, the expensive procedure of manual reinsertion of the jacket is necessary. The stiffness of the jacket material may also prevent the desired tight wrapping of the jacket around the book by pushing the cover away from the joint area. The latter problem is particularly prevalent with thick or laminated jacket materials and imparts an unsightly appearance to the book while also having an adverse effect upon subsequent processing and final handling.
It is to be noted that the prior art technique exemplified by German Pat. No. 1,103,294 also contemplates that the jackets be folded prior to being wrapped about the book with the fold conforming to the spacing, between opposite side edges, of the covers of the book. While this prefolding technique may result in reducing the resiliency of the flaps, it does not preclude the possibility of the fold slipping across an edge of the cover nor does it insure that the jacket will be wrapped tightly enough to substantially conform to the book. Such slippage and the inability to achieve tight wrapping may be attributable to unavoidable manufacturing tolerances for both the block and cover portions of the book. Restated, in many cases dimensional agreement between the required and often variable spacing between the folds of the jacket and adjustment of the folding devices cannot be insured.
An alternative prior art method of applying jackets to books is disclosed in German Pat. No. 958,107. In this alternative method the books are arranged with their spines facing upwardly and their covers opened to an angle of 90.degree.. During the course of application, the jackets are turned about heated bars located underneath the covers; such heated bars projecting past the edge of the cover by a preset length which is dependent upon the slack in the cover required to permit the closing of the jacket-fitted book. Although the use of heat during the folding or creasing operation reduces the resiliency of the jacket material in the fold area, adjustments of the apparatus which will preclude the possibility of either loose wrapping or the slipping out of the folds caused by wrapping too tightly is not possible. These problems; i.e., either unduly loose or too tight a wrapping; will occur when the spacing between the heated bars does not rather accurately coincide with the distance between the edges of the book cover plus an allowance for manufacturing tolerances as required to permit closing of the book and achievement of a neat appearance.